First fossil gravid turtle provides insight into the evolution of reproductive traits in turtles

Here we report on the first discovery of shelled eggs inside the body cavity of a fossil turtle and on an isolated egg clutch, both referable to the Cretaceous turtle Adocus. These discoveries provide a unique opportunity to gain insight into the reproductive traits of an extinct turtle and to understand the evolution of such traits among living turtles. The gravid adult and egg clutch indicate that Adocus laid large clutches of rigid-shelled spherical eggs and established their nests near rivers, traits that are shared by its closest living relatives, the soft-shelled turtles. Adocus eggshell, however, was probably more rigid than that of living turtles, based on its great thickness and structure, features that may represent unique adaptations to intense predation or to arid nest environments. In light of the reproductive traits observed in Adocus, the distribution of reproductive traits among turtles reveals that large clutches of rigid-shelled eggs are primitive for hidden-necked turtles (cryptodirans) and that spherical eggs may have evolved independently within this group.     

A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group

Evolutionary transitions to marine habitats occurred frequently among Mesozoic reptiles. Only one such clade survives to the present: sea turtles (Chelonioidea). Other marine turtles originated during the Mesozoic, but uncertain affinities of key fossils have obscured the number of transitions to marine life, and the timing of the origin of marine adaptation in chelonioids. Phylogenetic studies support either a highly‐inclusive chelonioid total‐group including fossil marine clades from the Jurassic and Cretaceous (e.g. protostegids, thalassochelydians, sandownids) or a less inclusive chelonioid total‐group excluding those clades. Under this paradigm, these clades belong outside Cryptodira, and represent at least one additional evolutionary transition to marine life in turtles. We present a new phylogenetic hypothesis informed by high resolution computed tomographic data of living and fossil taxa. Besides a well‐supported Chelonioidea, which includes protostegids, we recover a previously unknown clade of stem‐group turtles, Angolachelonia, which includes the Late Jurassic thalassochelydians, and the Cretaceous–Palaeogene sandownids. Accounting for the Triassic Odontochelys, our results indicate three independent evolutionary transitions to marine life in non‐pleurodiran turtles (plus an additional two‐three in pleurodires). Among all independent origins of marine habits, a pelagic ecology only evolved once, among chelonioids. All turtle groups that independently invaded marine habitats in the Jurassic–Cretaceous (chelonioids, angolachelonians, bothremydid pleurodires) survived the Cretaceous–Palaeogene mass extinction event. This highlights extensive survival of marine turtles compared to other marine reptiles. Furthermore, deeply‐nested clades such as chelonioids are found by the middle Early Cretaceous, suggesting a rapid diversification of crown‐group turtles during the Early Cretaceous.     

Triassic turtle tracks and the origin of turtles

Turtle (Testudines) tracks, Chelonipus torquatus, reported from the early Middle Triassic (Anisian) of Germany, and Chelonipus isp. from the late Early Triassic (Spathian) of Wyoming and Utah, are the oldest fossil evidence of turtles, but have been omitted in recent discussions of turtle origins. These tracks provide significant clues as to how early the turtle Bauplan originated. Turtle trackways are quite distinctive: the manus and pes form tracks nearly parallel to the midline and indicate an unusually wide gait in which the trackway width is nearly equal to the stride length. These tracks do not fit what would be expected to be made by Triassic Pappochelys or Odontochelys, a supposed prototurtle and an early turtle, respectively. In contrast, these tracks are consistent with what would be expected from the Triassic turtles Proganochelys and Palaeochersis. The features inferred to be present in Triassic turtle tracks support the notion that Odontochelys is a derived aquatic branch of the turtle stem lineage rather than the ancestral state of all turtles. Chelonipus also resembles the Permian track Pachypes dolomiticus, generally assigned to a pareiasaur trackmaker. These revelations highlight the need to consider all available evidence regarding turtle origins, rather than just the body fossils.     

Marine‐derived Nutrients from Green Turtle Nests Subsidize Terrestrial Beach Ecosystems

Spatially separated ecosystems are often linked by nutrient fluxes. Nutrient inputs may be transferred by physical vectors (i.e., wind and water) or by biotic vectors. In this study, we examine the role of green turtles (Chelonia mydas) as biotic transporters of nutrients from marine to terrestrial ecosystems, where they deposit eggs. We compare low and high nest density sites at Tortuguero, Costa Rica, the largest green turtle rookery in the western hemisphere. Four plant species (Costus woodsonii, Hibiscus pernanbucensis, Hymenocallis littoralis, Ipomoea pes‐caprae) were analyzed at both nest density sites for ¹⁵N, total carbon, nitrogen, and phosphorus, and vegetation cover. Sand was analyzed for ¹⁵N and total nitrogen. Vegetation at high nest density sites had higher total nitrogen, which was correlated with higher δ¹⁵N values, suggesting nutrient input from a marine source. The dominant plant species changed between low and high nest density sites, indicating that turtle‐derived nutrients may alter the plant community composition. The trend in δ¹⁵N values of sand was similar, although less pronounced than that of the vegetation. Sand may be a poor integrator of nutrient input due to low nutrient adsorption and high rate of leaching. Sea turtles have previously been shown to deposit considerable amounts of nutrients and energy on nesting beaches. In this study, we estimate annual nitrogen and phosphorus contributions at Tortuguero are 507 and 45 kg/km, respectively, and we demonstrate that beach vegetation likely assimilates a portion of these marine‐derived nutrients.     

Distribution and abundance of marine turtles in the Socialist Republic of Viet Nam

To establish baseline data on the distribution, abundance and threats to marine turtles in Viet Nam we conducted surveys with local fishers, community members and provincial Ministry of Fisheries staff from 17 of Viet Nam’s 29 coastal provinces. These data indicate that five species of marine turtle reside in Viet Nam’s waters (loggerhead, olive ridley, leatherback, green and hawksbill turtles), and four species nest on Viet Nam’s beaches (all of the above except the loggerhead turtle). It is evident from these data that significant declines have occurred in both foraging and nesting populations of all five marine turtle species found in Viet Nam. The greatest current threats to marine turtle populations in Viet Nam are habitat degradation, the accidental and opportunistic of turtles capture by fishers and the direct take of nesting females and their eggs. Successful conservation efforts have been made in recent years through collaboration between international Non Government Organisations and several Vietnamese Government Ministries. Continued success of these projects and the development and implementation of marine conservation policy will depend upon building awareness among Government employees, fishers and the general public about marine turtle biology, ecology, and the need to protect them.     

Variation in reproductive output of marine turtles

Most marine turtle species are non-annual breeders and show variation in both the number of eggs laid per clutch and the number of clutches laid in a season. Large levels of inter-annual variation in the number of nesting females have been well documented in green turtle nesting populations and may be linked to environmental conditions. Other species of marine turtle exhibit less variation in nesting numbers. This inter-specific difference is thought to be linked to trophic status. To examine whether individual reproductive output is more variable in the herbivorous green turtle (Chelonia mydas Linneaeus 1758) than the carnivorous loggerhead (Caretta caretta Linneaeus 1758), we examined the nesting of both species in Cyprus over nine seasons. Green turtles showed slower annual growth rates (0.11 cm year⁻¹ curved carapace length (CCL) and 0.27 cm year⁻¹ curved carapace width (CCW)) than loggerhead turtles (0.36 cm year⁻¹ CCL, 0.51 cm year⁻¹ CCW). CCL was highly correlated to mean clutch size in both green (R²=0.51) and loggerhead turtles (R²=0.61) and maximal clutch size of green turtles (R²=0.58). Larger females did not lay a greater number of clutches or have a shorter remigration interval than smaller females of either species. On average, the size of green turtle clutches increased and that of loggerhead turtles decreased as the season progressed. Individual green turtles, however, produced more eggs per clutch through the season to a maximum in the third or fourth clutch. In loggerhead turtles, clutches 1-4 were very similar in size but the fifth clutch was 38% smaller than the first. No individuals of either species were recorded laying more than five clutches. Green turtles may not be able to achieve their maximum reproductive output with respect to clutch size throughout the season, whereas only loggerhead turtles laying five clutches (n=5) appear to become resource depleted. Green turtles nesting in years when large numbers of nests were recorded laid a greater number of clutches than females nesting in years with lower levels of nesting.     

Multiple paternity in egg clutches of hawksbill turtles (Eretmochelys imbricata)

We present the first data collected on the genetic mating system of the hawksbill turtle Eretmochelys imbricata, the only marine turtle not studied to date. We examined paternity within 12 egg clutches from ten female hawksbill turtles from Sabah Turtle Islands, Malaysia. A total of 375 hatchlings were analysed using five microsatellite markers. Results demonstrated that clutches from two out of ten females were sired by multiple males (maximum of two). Although at a low frequency, observation of multiple paternity indicates that hawksbill turtles exhibit the same genetic mating system (polyandry) as observed for other species of marine turtles. Consistent paternity across multiple clutches laid by individual females in one breeding season supports the hypothesis that sperm are stored from mating prior to nesting and are then used to fertilize all subsequent clutches of eggs that season.     

Seasonal Variation in Sea Turtle Density and Abundance in the Southeast Florida Current and Surrounding Waters

Assessment and management of sea turtle populations is often limited by a lack of available data pertaining to at-sea distributions at appropriate spatial and temporal resolutions. Assessing the spatial and temporal distributions of marine turtles in an open system poses both observational and analytical challenges due to the turtles’ highly migratory nature. Surface counts of marine turtles in waters along the southern part of Florida’s east coast were made in and adjacent to the southeast portion of the Florida Current using standard aerial surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular concern for sea turtles as interest increases in offshore energy developments, specifically harnessing the power of the Florida Current. While it is understood that marine turtles use these waters, here we evaluate seasonal variation in sea turtle abundance and density over two years. Density of sea turtles observed within the study area ranged from 0.003 turtles km^-2 in the winter of 2011 to 0.064 turtles km^-2 in the spring of 2012. This assessment of marine turtles in the waters off southeast Florida quantifies their in-water abundance across seasons in this area to establish baselines and inform future management strategies of these protected species.     

DNA barcodes for globally threatened marine turtles: a registry approach to documenting biodiversity

DNA barcoding is a global initiative that provides a standardized and efficient tool to catalogue and inventory biodiversity, with significant conservation applications. Despite progress across taxonomic realms, globally threatened marine turtles remain underrepresented in this effort. To obtain DNA barcodes of marine turtles, we sequenced a segment of the cytochrome c oxidase subunit I (COI) gene from all seven species in the Atlantic and Pacific Ocean basins (815 bp; n = 80). To further investigate intraspecific variation, we sequenced green turtles (Chelonia mydas) from nine additional Atlantic/Mediterranean nesting areas (n = 164) and from the Eastern Pacific (n = 5). We established character-based DNA barcodes for each species using unique combinations of character states at 76 nucleotide positions. We found that no haplotypes were shared among species and the mean of interspecific variation ranged from 1.68% to 13.0%, and the mean of intraspecific variability was relatively low (0–0.90%). The Eastern Pacific green turtle sequence was identical to an Australian haplotype, suggesting that this marker is not appropriate for identifying these phenotypically distinguishable populations. Analysis of COI revealed a north–south gradient in green turtles of Western Atlantic/Mediterranean nesting areas, supporting a hypothesis of recent dispersal from near equatorial glacial refugia. DNA barcoding of marine turtles is a powerful tool for species identification and wildlife forensics, which also provides complementary data for conservation genetic research.     

Predation by White Sharks Carcharodon carcharias (Chondrichthyes: Lamnidae) Upon Chelonians, with New Records from the Mediterranean Sea and a First Record of the Ocean Sunfish Mola mola (Osteichthyes: Molidae) as Stomach Contents

The occurrence of marine turtles in the diet of white sharks, Carcharodon carcharias, is reviewed worldwide. Four records of chelonians eaten by white sharks in the Mediterranean Sea are described, which on the basis of carapace remnants confirmed both the loggerhead Caretta caretta and green turtle Chelonia mydas to be preyed upon in those waters. The condition of these remains indicates that large white sharks can ingest turtles essentially intact. As well as falling prey to white sharks, we suspect that some interactions involve turtles being grab-released in a non-predatory mannner and their survivability from such low-intensity bites or other mouthings may be quite high. The white shark may be the chief marine predator of adult chelonians in the Mediterranean Sea, albeit the impact of this predation upon turtle populations is nominal compared to other sources of mortality. Further, we give an account describing an adult ocean sunfish, Mola mola, in the stomach of a white shark taken in Italian waters.     

Predicted distributions and abundances of the sea turtle ‘lost years’ in the western North Atlantic Ocean

Oceanic dispersal characterizes the early juvenile life-stages of numerous marine species of conservation concern. This early stage may be a ‘critical period’ for many species, playing an overriding role in population dynamics. Often, relatively little information is available on their distribution during this period, limiting the effectiveness of efforts to understand environmental and anthropogenic impacts on these species. Here we present a simple model to predict annual variation in the distribution and abundance of oceanic-stage juvenile sea turtles based on species’ reproductive output, movement and mortality. We simulated dispersal of 25 cohorts (1993–2017) of oceanic-stage juveniles by tracking the movements of virtual hatchling sea turtles released in a hindcast ocean circulation model. We then used estimates of annual hatchling production from Kemp's ridley Lepidochelys kempii (n = 3), green Chelonia mydas (n = 8) and loggerhead Caretta caretta (n = 5) nesting areas in the northwestern Atlantic (inclusive of the Gulf of Mexico, Caribbean Sea and eastern seaboard of the U.S.) and their stage-specific mortality rates to weight dispersal predictions. The model's predictions indicate spatial heterogeneity in turtle distribution across their marine range, identify locations of increasing turtle abundance (notably along the U.S. coast), and provide valuable context for temporal variation in the stranding of young sea turtles across the Gulf of Mexico. Further effort to collect demographic, distribution and behavioral data that refine, complement and extend the utility of this modeling approach for sea turtles and other dispersive marine taxa is warranted. Finally, generating these spatially-explicit predictions of turtle abundance required extensive international collaboration among scientists; our findings indicate that continued conservation of these sea turtle populations and the management of the numerous anthropogenic activities that operate in the northwestern Atlantic Ocean will require similar international coordination.     

Relationship between tropical cyclones and the distribution of sea turtle nesting grounds

Aim This study examines the relationship between the distribution of existing sea turtle nesting sites and historical patterns of tropical cyclone events to investigate whether cyclones influence the current distribution of sea turtle nesting sites. The results, together with information on predicted cyclone activity and other key environmental variables, will help in the identification and prediction of future nesting sites for sea turtles as changes to the coastal environment continue. Location Queensland, Australia. Methods We used data on the nesting distribution of seven populations of four species of sea turtles [green (Chelonia mydas), flatback (Natator depressus), hawksbill (Eretmochelys imbricata) and loggerhead (Caretta caretta)] from the eastern Queensland coast, and tropical cyclone track data from 1969 to 2007 to explore the relationship between (1) sea turtle nesting phenology and cyclone season, and (2) sea turtle nesting sites and cyclone distribution. Furthermore, using two green turtle populations as a case study, we investigated the relationship between cyclone disturbance and sea turtle reproductive output, nesting site and season. Bootstrapping was used to explore if current sea turtle nesting sites are located in areas with lower or higher cyclone frequency than areas where turtles are currently not nesting. Results All populations of sea turtles studied here were disturbed by cyclone activity during the study period. The exposure (frequency) of tropical cyclones that crossed each nesting site varied greatly among and within the various sea turtle populations. This was mainly a result of the spatial distribution of each population’s nesting sites. Bootstrapping indicated that nesting sites generally have experienced lower cyclone activity than other areas that are available for nesting. Main conclusions Tropical cyclones might have been sufficiently detrimental to sea turtle hatching success on the eastern Queensland coast that through a natural selection process turtles in this region are now nesting in areas with lower cyclone activity. Therefore, it is important that future studies that predict climate or range shifts for sea turtle nesting distributions consider future cyclone activity as one of the variables in their model.     

The exposure of green turtles (Chelonia mydas) to tumour promoting compounds produced by the cyanobacterium Lyngbya majuscula and their potential role in the aetiology of fibropapillomatosis

Lyngbya majuscula, a benthic filamentous cyanobacterium found throughout tropical and subtropical oceans, has been shown to contain the tumour promoting compounds lyngbyatoxin A (LA) and debromoaplysiatoxin (DAT). It grows epiphytically on seagrass and macroalgae, which also form the basis of the diet of the herbivorous green turtle (Chelonia mydas). This toxic cyanobacterium has been observed growing in regions where turtles suffer from fibropapillomatosis (FP), a potentially fatal neoplastic disease. The purpose of this study was to determine whether green turtles consume L. majuscula in Queensland, Australia and the Hawaiian Islands, USA, resulting in potential exposure to tumour promoting compounds produced by this cyanobacterium. L. majuscula was present, though not in bloom, at nine sites examined and LA and DAT were detected in variable concentrations both within and between sites. Although common in green turtle diets, L. majuscula was found to contribute less than 2% of total dietary intake, indicating that turtles may be exposed to low concentrations of tumour promoting compounds during non-bloom conditions. Tissue collected from dead green turtles in Moreton Bay tested positive for LA. An estimated dose, based on dietary intake and average toxin concentration at each site, showed a positive correlation for LA with the proportion of the population observed with external FP lesions. No such relationship was observed for DAT. This does not necessarily demonstrate a cause and effect relationship, but does suggest that naturally produced compounds should be considered in the aetiology of marine turtle FP.     

Cofán Indians’ Monitoring of Freshwater Turtles in Zábalo,Ecuador

The Cofán Indians of Aguarico and Zábalo Rivers in Ecuador in 1990 began a turtle recuperation effort by raising turtle hatchlings (Podocnemis expansa and P. unifilis) in small pools. To evaluate the effectiveness of this program, the Cofán developed and tested three methods to document changes in the populations of turtles. The first method consisted of interviews with people from neighbouring communities about their perceptions of changes in turtle abundance. The second method was a direct count of turtles observed along the rivers from canoe. The third method was an indirect count, involving turtle nest censusing along community beaches. Two of the methods yielded numerical, statistically positive turtle population trends. The turtle program has influenced the community's perception of turtle conservation issues so that, instead of hunting the adults and eggs, they now protect them. The training in record-keeping permits them to make a transparent history of the equitability of access to the turtle egg resource. The Cofán monitoring experience strengthened their successful petition to the Ecuadorian government for the rights to manage their territorial lands within the Cuyabeno Wildlife Reserve, and to receive protected area status and management rights to other ancestral lands. The experience gained by the Zábalo monitors is now serving as a model for the design and implementation of the park monitoring system of the newly-established Cofán Park Ranger Corps, which will be patrolling three Ecuadorian Ecological Reserves which overlap Cofán inhabited areas.     

Invertebrate infestation on eggs and hatchlings of the loggerhead turtle, Caretta caretta, in Dalaman, Turkey

The damage caused by some invertebrates to the eggs and hatchlings of loggerhead turtles, Caretta caretta, was investigated during the summer of 2002 on Dalaman beach, Turkey. The specimens, identified to family or genus levels, from nine families representing seven orders were recorded as infesting nests of loggerhead turtles. The heaviest impacts on loggerhead turtle nests was made by Pimelia sp. (Tenebrionidae, Coleoptera). Twenty-four (36.3%) out of 66 intact loggerhead hatched nests were affected by these larvae. Larval damage by Pimelia sp. was recorded in 188 (10.6%) out of 1773 eggs, but only in two (0.28%) hatchlings. The results show that fewer insects were in the nest the further from vegetation and therefore the relocation of nests from the water's edge to further inland close to vegetation may increase the infestation rate of the eggs.     

Development and characterization of ten novel microsatellite markers from olive ridley sea turtle (Lepidochelys olivacea)

Olive ridleys, one of the widely distributed marine turtle species has undergone declines in recent years due to multiple anthropogenic factors warranting conservation efforts for which assessment of genetic variability in existing populations become critical. Here we describe development of ten new microsatellite markers from a short sequence repeat-enriched partial genomic DNA library, which are found to be highly informative for genetic studies. Eight of these markers when tested on 83 olive ridley turtles revealed high allelic diversity (4–27 alleles per marker), and high observed and expected heterozygosity estimates that ranged from 0.29 to 0.82 and 0.62 to 0.94, respectively. Two microsatellites were monomorphic in the tested olive ridley samples, but were found to be informative/polymorphic when tested on related marine turtle species. More importantly, nine of the new markers showed robust cross-species amplifications in three related species Dermochelys coriacea, Chelonia mydas and Eretmochelys imbricata. Thus, this study describes ten new microsatellite markers and also demonstrates their potential as efficient genetic markers in studies related to parentage analysis, population structure, phylogeography and species relationships of olive ridleys and other marine turtle species.     

An unusual pattern of limb morphology in the Tithonian marine turtle Neusticemys neuquina from the Vaca Muerta Formation,Neuquén Basin,Argentina

de la Fuente M.S. & Fernández, M.S. 2010: An unusual pattern of limb morphology in the Tithonian marine turtle Neusticemys neuquina from the Vaca Muerta Formation, Neuquén Basin, Argentina. Lethaia, Vol. 44, pp. 15–25. Here, we report an unusual pattern in the manus and pes morphology of the Tithonian marine turtle Neusticemys neuquina. We analyse the forelimbs of two previously known specimens and describe the hind limbs of two previously undescribed specimens. Neusticemys neuquina is characterized by a relative elongation of both the forelimb and hind limb, compared with stem Chelonoidea, as well as an elongation of the pedal digit V, achieved through the elongation of the bones, as well as a moderate hyperphalangy. The elongation of pedal digit V is the most striking feature of N. neuquina, a feature unknown in other turtles. □Limb morphology, Neusticemys neuquina, Tithonian turtle.     

Bacteriophage versus antibiotic therapy on gut bacterial communities of juvenile green turtle,Chelonia mydas

Green turtles are endangered marine herbivorous hindgut fermenters that contribute to a variety of marine ecosystems. Debilitated turtles are often rehabilitated in turtle hospitals. Since accurate diagnosis of disease is difficult, broad-spectrum antibiotics are routinely used as a general treatment, potentially causing collateral damage to the gut microbiome of the patient. Here, we evaluated the concept of the application of bacteriophage (phages) to eliminate targeted intestinal bacteria as an alternative to a broad-spectrum antibiotic (enrofloxacin) in clinically healthy, captive green turtles. Additionally, the impact of a broad-spectrum antibiotic (enrofloxacin) and phage therapy on the gut bacterial communities of green turtles was evaluated. Gut bacterial communities in faecal samples were analysed by sequencing the V1-V3 regions of the bacterial 16S rRNA. Bacteria-specific phage cocktails significantly (P < 0.05) reduced targeted Acinetobacter in phage-treated turtles during the therapy. Compared to control, no significant difference was observed in the bacterial diversity and compositions in phage-treated turtles. In contrast, bacterial diversity was significantly (P < 0.05) reduced in antibiotic-treated turtles at day 15 and throughout the trial. The alteration in the bacterial microbiota of antibiotic-treated turtles was largely due to an increase in abundance of Gram-positive Firmicutes and a concurrent decrease in Gram-negative Bacteroidetes, Proteobacteria and Verrucomicrobia. Additionally, we observed the relative abundance of several bacteria at lower taxonomic level was much less affected by phages than by antibiotics. These data offer the proof of concept of phage therapy to manipulate transient as well as indigenous bacterial flora in gut-related dysbiosis of turtles.     

Impacts of a geotextile container dune core on marine turtle nesting in Juno Beach,Florida, United States

Hard armoring technologies (e.g. rock revetments and seawalls), which are installed to protect homes from beach erosion, can diminish the aesthetics and amenity of the beach. Over time, these structures cause beach narrowing and often prevent marine turtle access to nesting habitat altogether. An alternative armoring technology, known as geotextile dune core systems (or geocores), has been developed and implemented to protect inland infrastructure from beach erosion, yet there remains an absence of research on possible effects on marine turtles. In this study, we examined the impacts of a geocore installed on Juno Beach, Florida, United States in February 2014 on loggerhead (Caretta caretta) and green turtle (Chelonia mydas) nesting success, hatching success, and emergence success. A before‐after‐control‐impact paired series design evaluated the difference in nesting success per week for the impact and control sites 4 years before (2010–2013) and 4 years after (2014–2017) the installation of the geocore. Neither loggerhead nor green turtle nesting success was significantly different after the installation of the geocore; however, when analyzing loggerhead crawls that came to within 5 m of the geotextile bags, nesting success decreased. Neither hatching nor emergence success was significantly different after the installation of the geocore for either species. Our results suggest that geocores may minimally affect loggerhead and green turtles and provide a suitable restoration technique for homeowners facing beach erosion.     

Novel cDNA sequences of aryl hydrocarbon receptors and gene expression in turtles (Chrysemys picta and Pseudemys scripta) exposed to different environments

Reproductive changes have been observed in painted turtles from a site with known contamination located on Cape Cod, MA, USA. We hypothesize that these changes are caused by exposure to endocrine-disrupting compounds and that genes involved in reproduction are affected. The aryl hydrocarbon receptor (AHR) is an orphan receptor that is activated by environmental contaminants. AHR mRNA was measured in turtles exposed to soil collected from a contaminated site. Adult turtles were trapped from the study site (Moody Pond, MP) or a reference site and exposed to laboratory environments containing soil from either site. The red-eared slider was used to assess neonatal exposure to soil and water from the sites. The environmental exposures occurred over a 13-month period. Juveniles showed an age-dependent increase in brain AHR1. Juvenile turtles exposed to the MP environment had elevated gonadal AHR1. Adult turtles exposed to the MP environment showed significantly decreased brain AHR2. The painted turtle AHR is the first complete reptile AHR cDNA sequence. Phylogenetic analysis of the painted turtle AHR showed that it clusters with other AHR2s. Partial AHR1 and partial AHR2 cDNA sequences were cloned from the red-eared slider. MEME analysis identified 18 motifs in the turtle AHRs, showing high conservation between motifs that overlapped functional regions in both AHR isoforms.